A major cause of mortality in transplant recipients is fungal infection. One aim of the CDC is to determine the epidemiology of fungal infections in transplant recipients, with a view to developing strategies aimed at preventing such infections. A major thrust of this project will be to perform surveillance for fungal infections so that the epidemiology can be precisely determined. Transplant immunosuppressive regimens are undergoing a paradigm shift whereby immunosuppression reaches levels seen in advanced AIDS (CD4 counts of less than 50 Cells/mm3) in the early months post transplant and then is significantly reduced for the remainder of the life of the transplant recipient. The study of fungal infections in this setting is particularly important. Although one strategy of prevention is use of prophylactic antifungal agents, an alternative approach is to find a means of diagnosis of fungal infections while they are still at a treatable stage. Therefore, another major aim of the study is to serially collect serum and urine on consecutive transplant recipients with a view to having a "bank" on which to test new diagnostic methodologies.